1. Field of the Invention
The present invention in general relates to peripheral expansion systems, and more particularly this invention relates to a system and method for remotely power cycling a peripheral expansion subsystem.
2. Description of the Related Art
Computer systems such as laptop, workstations and severs typically include a processor, memory, and local bus over which the processor communicates with peripheral devices attached or connected to the computer system. For example, the PCI or peripheral component interconnect is one industry standard which provides a high performance, local bus architecture at a low cost. It is intended to be a common I/O component interface across different platforms. The PCI interface, however, is subject to several limitations. One such limitation is that the PCI bus has been architected to connect components located close to one another. Typically, the components need to be within a certain distance of each other. In addition, the trace length for peripheral add-in devices is limited to 1.5 inches from the motherboard of the computer for the PCI signal and 2.5 inches for the primary clock. This limitation is to ensure proper timing of the PCI signal to and from the peripheral device, and is documented in the PCI Local Bus Specification Revision 2.1—Production Version, Dated Jun. 1, 1995. Lastly, there is a limitation to the number of loads that can be presented to the PCI local bus. The current PCI bus specification limits the maximum number of add in cards to four when operating at 33 MHz, and to two when operating at 66 MHz. In higher end computer systems or servers that have a higher number of peripheral devices or field replaceable units (FRUs) and perform I/O operations at higher bandwidth, these limitations have significant impact. Often, there are simply not enough expansion slots in the system to accommodate the peripheral devices desired.
To address such limitations, peripheral subsystems may be used. A peripheral subsystem connects to a host or computer system and allows for additional slots for peripheral components. A host interface card occupies a PCI compliant slot in the host system and expansion system, and connects the two over a transmission medium. See, for example, U.S. Pat. No. 5,781,747 issued to Smith et al., and U.S. Pat. No. 5,764,924 issued to Hong.
A peripheral subsystem typically must operate when the corresponding host system is operational, for example, powered up. In many environments, the powering up of the peripheral subsystem must be synchronized to the host system's power up event. This requirement may be critical if the host system executes boot-up firmware and/or operating system load initialization programs, whereby the hardware configuration must be recognized and/or the software device drivers must be installed.
This synchronized event can be readily accomplished by manually powering up the peripheral subsystem first, followed by the manual power up of the host system.
There are many other system application environments, where it is also highly desirable and/or a system requirement that this synchronized event be possible without manual intervention, for example in a remotely monitored data center. In these applications, the power up sequence is typically started via some form of communications link to the host itself, such as a modem line, serial line or a LAN connection. However, there is no assurances the peripheral subsystem will be powered up as needed by the host system. In addition, as there is a need to be able remotely synchronize the power up routine, there is also a need to remotely control the power down event.
Thus, there is a need in the art to address the power cycling needs of a peripheral expansion system. It can be seen that a peripheral subsystem needs to be remotely powered on when the host system it is connected to is powered on, and similarly the remote power system needs to be powered off when the host system is powered off. Moreover, to meet the high availability, minimal space utilization requirements of today's data centers, the power up and power down sequencing ability should be low cost, simple and easy to use.